JPS63159340A - Production of perfluoroacylfluoride - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing perfluoroacyl fluoride in which the acyl radical is a propionyl or butyryl group.

PRIOR ART AND ITS PROBLEMS Perfluoroacyl fluorides are intermediate products of considerable interest from a commercial point of view, for example as surfactants, with the aim of obtaining water- and oil-repellent products on coats and fabrics. For example, it can be used to produce flameproofing agents and emulsifiers for the polymerization of fluorinated olefins.

Perfluoroacyl fluorides can be obtained in various ways, in particular by electrochemical fluorination of carboxylic acids or their derivatives (chlorides, esters) and by starting from iodoperfluoroalkanes.

These processes are as reported in the paper "Preparation, Properties and Industrial Applications of Organofluorin Compounds" by R.E. Banks, Chapter 1, Ellishoughts Limited, Chichester. Usually expensive and, as in the case of electrochemical fluorination,
High yields and high purity cannot be achieved or, as in the case of starting from iodoperfluoroankane, many steps are required and it is necessary to start from expensive starting materials.

Purity is an essential requirement in perfluoroacyl fluorides, and lack of purity can prevent the use of these intermediate products in subsequent conversion reactions. For example, in the conversion to a perfluoroalkyl-fluorooxy compound, it is known that trace amounts of impurities cause explosive decomposition, and high purity is required.

7-/L/ ・x Nu-hei, ()v Schiff (RlN,
Hazeldine) and Ni E-f”) Ping (A, E, Tipping) (J, Chem,
Soc, (C), pp. 549-405, 196B)
reported the thermal decomposition rearrangement of trifluoromethyl trifluorovinyl ether at 595° C. in a platinum reactor. This reaction leads to the formation of several products, in particular perfluoropropionyl fluoride, this latter product being obtained in a yield of 53N.

An object of the present invention is to provide a method for producing perfluoroacyl fluoride in which the acyl radical is a propionyl or butyryl group with high yield and high selectivity.

Another objective is to provide a very pure product which makes purification operations unnecessary or very minimal, thus avoiding risks associated with instability of the product, e.g. hydrolysis. .

SUMMARY OF THE INVENTION These and further objects are achieved by the process of the present invention for producing perfluoroacyl fluorides in which the acyl radical is a propionyl or butyryl group. This process is characterized by heat treating a perfluoroalkyl vinyl ether whose alkyl radical is a methyl or ethyl group in the presence of a catalyst selected from the group consisting of: A) Li + Na t K + Cs or Fluoride of Rb or a compound of LI I Na +K, Cs or Rh that can be easily fluorinated under the reaction conditions; Is) Be e Mg e Ca e Sr or B
a fluoride, or a compound of Be e Mg tCa , Sr or 13a that can be easily fluorinated under the reaction conditions; C) fluoroaluminates and fluorosilicates of alkali metals or metals belonging to Group A of the periodic table; D) first transition; Fluorides of metals of the series (i.e. metals with atomic numbers 21 to 30), or the corresponding metals or compounds of said metals, which can be readily fluorinated under the reaction conditions; E) Fluorides of lanthanides. , or the corresponding metal or compound of said metal, which can be easily fluorinated under the reaction conditions; F) Sr + AI + Ti T Ge + S
n or Pb oxyfluoride, or SiH which can be readily fluorinated under the reaction conditions to yield one of the fluorides.
Compounds of Al + 'ri r Ge , Sn or Pb.

The reaction is as follows: (where RF is CF, or C2F5).

The metals and other easily fluorinated compounds used as catalysts generate fluorinated species in situ under the action of the perfluoroalkyl vinyl ether during the reaction φ. They can also be fluorinated with another reactant capable of fluorinating them, such as fluorine or hydrofluoric acid, before carrying out the reaction.

Ll*Na+K which can be easily fluorinated under the reaction conditions
, Cs, Rb, oxides, hydroxides and oxyhalides, such as L+20 + N
20 in a2O+, Cs 20,
LiOH, Na1l(, KOH, Cs0II.

Li0CI, Na0CI, KOCI and CsO
C I can be mentioned.

Be, Mg that can be easily fluorinated under the reaction conditions.

Among the compounds of Ca, Sr, Ba, oxides, hydroxides and oxyhalides, such as l3aO
, MgO.

CaO, SrO, Ba(OH)2. Mg(OII)2
．． Ca(011)2゜Sr(OH)2, l3a(O
CI)2, 84g (OCI)2. Ca(OCI)2
and S r (QCl ) 2 .

Among the fluoroaluminates, fluorosilicates, fluorotitanates and fluorometalates of alkali metals or metals belonging to group ff A of the periodic table, for example,
AlF6+ Cs, AII"6# I(2Sil'6+
Cs2SiF6+C5CuF, , KCuF, ,
CsN1F.

Preferred compounds in this category include AlF6. Cs3A
IF6°K2SiF6 and C52SiF6.

Among the compounds which can be fluorinated under the reaction conditions to give the above-mentioned fluoroaluminates, fluorosilicates, fluorotitanates or fluoromethanates, for example alkali metal and group IIA metal aluminates, silicates and Titanates, e.g. Na2
At204+ Na25in.

k,, AI 2041 MgAl 204 and Na2T
One example is ie5. Alkali metal or Part ■A
group metals and other metals such as Cu, Zn, Mg
mixed oxides such as MgO, CuOr N1
g00ZnO* K2O, CuO and CS 20 lM
Mention may also be made of gO.

Among the fluorides of metals of the first transition series, the following may be mentioned: CuF21, NiF2+ZnF
2*CoF2. CoF3+ CrF, , MnF
2*FeF2 and FeF3. Among the corresponding metals, for example Cu l Nt.

Zn, Cr, hin, Fe and Co can be mentioned, among which Cu*Ni+Zn and Fe are preferred.

The most preferred is Cu. Among compounds of such metals that can be readily fluorinated under the reaction conditions, for example oxides such as Fe203r CuO+ NiO+Cr2O
5+ CO2O3r Cu2Cr2O4* Hydroxide, e.g. Fed(OH), Cu(OH)2.
Ni(OH)2. Cry(OH).

Coo(OH) Nioxyhalide, e.g. Fe0C1
.

N1(OH)CI, Cr0C1, Cu(OR)CI
, Co(OH)CI.

Among the fluorinated nitrides, for example, LaF, , CeF
4 can be mentioned. Among the corresponding metals, mention may be made of lanthanum. Among the lanthanide compounds that can be easily fluorinated under the reaction conditions, eg oxides, eg La2O5*CeO2: oxide-hydroxides, eg Lad(OH), Ce0(OH)2:
hydroxides, e.g. La(OH), , C
e (01() 4 nioxyhalide, e.g. La0C
1, Ce0CI2.

Si + Al * Tt + Ge, Sn and P
Among the oxy7A/olides of b, 5iOxFy (2
x+y=4) is preferred. Among the compounds that can be readily fluorinated to give such oxyfluorides, the oxide, V]eha5io21 Al2O5*'1'i0
2 Nioxide-hydroxide, e.g. S+0x(OI
-Dy (2x + y-4), ノ\10x(OH)y
(2x+y=3) can be mentioned.

Instead of metals of the first transition series or lanthanides, alloys thereof, such as steel, brass, etc., can be used.

The most preferred preformed fluorination catalyst is Mg.
It is F2.

When using preformed fluoride as starting material,
It is often convenient to activate the fluoride in situ in the presence of the reactant itself, namely the perfluoroalkyl vinyl ether. When metals or non-fluorinated compounds are used as starting materials, treatment with the reactants themselves may be necessary, leading to both the formation of fluorinated compounds and the activation of at least a portion of the starting materials. Instead of the reactant itself, another fluorinating agent, such as F2 or HF, can be used to lead to the formation of fluoride and the activation of at least a portion of the starting material used.

Preferably, the metal or non-fluorinated compound is subjected to a heat treatment before being subjected to the fluorination and activation treatment. This heat treatment is carried out in the temperature range 300° to 65°C for metals.
Due to their chemical and physical stability in the case of other fluorinable compounds, it is customary to carry out the process at temperatures ranging from 250° to 500°C.

The duration of such heat treatment is typically in the range of 1 to 3 hours.

Already fluorinated catalysts can also be thermally activated. This activation is usually carried out at the same temperature at which the reaction occurs or at a higher temperature.

The temperature range over which the reaction can be carried out can vary depending on the catalyst and can depend on the chemical nature, physical form and degree of activation of the catalyst.

Generally, conversion tends to increase with increasing temperature, while selectivity increases up to a given value of temperature and then decreases at higher temperatures. Therefore, for each catalyst,
While there is a temperature range in which good results are obtained and a high yield of perfluoroacyl fluoride is obtained, there is a narrower temperature range in which the best combination of conversion and selectivity is achieved.

For metals of the first transition series, good results are usually 300
It is obtained within the range of 500 °C to 500 °C, and Cu.

For Ni, Zn and Fe, the best results are usually
Obtained at a temperature of 350° to 450°C.

3i + Al e Tie Ge + Sn and sb
oxyfluoride and Si, Al t, which easily fluorinate to form a nuclear oxyfluoride under the reaction conditions.
'l'i e Ge #For compounds of Sn and Pb,
Good results are usually obtained at temperatures of 250° to 400°C; in the case of fluorinated silicas, best results are obtained at temperatures of 300° to 400°C.

For Be + Mg, Ca, Sr and Ba fluorides and compounds that can be easily fluorinated under the reaction conditions, good results are usually obtained at temperatures between 300° and 450°C.
For MgF2, the best results were obtained for 3
Obtained between 50° and 450°C.

Li t Na + K * Cs and Rb fluoride and Ls HNa which can be easily fluorinated under the reaction conditions
*For K+Cs and nb compounds, good results are usually obtained within the temperature range 300° to 450°C, KF
, the preferred operating range is 520° to 360°C.

Activation temperatures and times vary from catalyst to catalyst.

Activation usually becomes faster as the temperature increases. In the case of preformed catalysts, activation is usually carried out at the same temperature at which the reaction is carried out. Fluorination and activation of the metal or other fluorinable compound is also typically carried out at the same temperature at which the reaction is carried out.

The particle size and physical shape of the catalyst are not critical. Particle size 250
It is common to use catalysts in the range of 50 microflons and up. When the catalyst is metal, it can be in the form of dimensional filaments, chips, needles, etc. The metal hexagonal surface can be smooth or exhibit a predetermined porosity with a specific surface area, for example, in the range from 0.05 to 0.1 m2/jq.

Fluorinated catalysts can be mixed with metals and used in a similar manner. Such metals include those which upon fluorination give rise to the catalyst according to the invention, such as Cu, Ni and other metals,
For example, it can be made of both metals, such as AI. The presence of metal helps remove heat from the reaction medium.

Alternatively, the fluorinated catalyst can be supported on a metallic material. The method for manufacturing the steel-supported fluorination catalyst is to form a filament or needle or granule oxide with a diameter in the range of 25,050 mf to wing.
(CuO or CuzO or a mixture thereof) is reduced with hydrogen diluted with nitrogen at a temperature of 250° to 350°C, thus reducing the specific surface to, for example, Q, 05 to 0.1.
The purpose is to obtain a carrier composed of porous metallic copper of m2/g. This carrier is then impregnated with a solution (eg, an aqueous or alcoholic solution) of a fluoride, such as NaF. Finally, the used bath medium is evaporated under vacuum.

Either a single catalyst or a mixture of catalysts can be used in the process of the invention. The process can be carried out batchwise or preferably continuously. If the process is carried out batchwise, the reaction can be carried out in an autoclave, operating under endo-geneous pressure developed by the system.

Preferably, the process is carried out continuously, with a stream of perfluoroalkyl vinyl ether flowing in the gas phase over the catalyst bed.

The perfluoroalkyl vinyl ether can be used alone or with a gaseous diluent that is inert under the reaction conditions, such as N2+ He
Alternatively, it can be used as a mixture with CF4. If a diluent is used, the perfluoroalkyl vinyl ether/diluent volume ratio is comprised, for example, within the range of 100:1 to 1:1. When a gaseous stream of perfluoroalkyl vinyl ether is flowed over the catalyst bed, the warp flow value is comprised within the range of α025 to αIN# 7 hours per gram of catalyst.

The contact time of the reactants with the catalyst depends on the method used (batchwise or continuous), the nature of the catalyst, the physical form of the catalyst, the possible distribution of the reactants, and the reaction temperature. can vary within a wide range.

If the process is carried out continuously under steady-state conditions on an already activated catalyst with reactant flow rates in the range α025 to αI Nl 7 hours/gram of catalyst, the contact time can vary, e.g.
It can be in the 90 second range.

The inventive catalyst is endowed with a long active life. By the process of the present invention, conversion rates of up to approximately 99% and approximately 90%
Selectivity up to % can be obtained.

? & The impurities present in the final product consist mostly of unreacted novel fluoroalkyl vinyl ethers and fluorinated olefins. These impurities can be removed using conventional techniques.

Fluorinated olefins can be separated, for example, by bubbling the gaseous reaction mixture into liquid bromine, and the unsaturated product becomes a liquid brominated compound, which can be separated, for example, by distillation.

The main advantages of the present invention can be summarized as follows: the knee reaction can be carried out at a lower temperature than in the absence of a catalyst; The production of many by-products, sometimes perfluoroisobutyne, can be controlled and limited to very low amounts by operating at lower temperatures. Perfluoroisobutyne is highly toxic and its formation cannot be avoided in catalytic pyrolysis processes;-
The final product can be refined in a simple and effective manner to remove more impurities, ie unsaturated impurities; one imparts a long active life to the catalyst.

Example 1 In all examples, the length is 250 m and the inner diameter is 10.9 m.
A tubular reactor of m is used. A new reactor was used in each run.

Example 1 uses an unfilled reactor casing of steel Al51316. A 6 t reactor was preheated at 300°C for 2 hours under an atmosphere of N2 and then heated to a controlled temperature of 380°C for 14 hours.
make a clause Perfluoromethyl vinyl ether is fed to the reactor in stream*a, 6 Nl/h. 1. I
t, detected by spectrophotometer and gas mass spectrometry. The gas is analyzed online in the gas phase by gas chromatography. Five minutes after the start of supply, the conversion rate was 499X and the selectivity to perfluoropropionyl fluoride was 0. I'm on the il side. After an additional 50 minutes, the conversion is 695% and the selectivity is 494%.

Trials demonstrate the nonselectivity of the thermal process and the in situ generation of active catalyst rods over time in the presence of reactants.

The process was carried out in an Al51316 steel reactor in Example 1.
Do as follows. Use the conditions shown below. The table also reports the results obtained.

Total hours, minutes 311 60 90 12015
0 temperature, °C 395 400 400 400 400 Conversion rate, % 74.8 85 89.6 914
96.5 Selectivity, X/>7 68A 825
The 82.7 8t1 test demonstrates the production of catalytic species and the progressive activity of the catalytic species, resulting in an increase in selectivity and group yield.

Example 3 The reaction is carried out in a copper reactor filled with copper needles having lengths ranging from 1 to 10 inches. The packed reactor is thermally pretreated at 300° C. for 3 hours under nitrogen atmosphere. The reactor was then adjusted to a controlled temperature of 390°C and perfluoromethyl vinyl ether was flowed into the reactor.
Feed in Nl/h. The results obtained as a function of time are reported in the table below.

6- Total time, minutes 5 50 80 120 Conversion rate, X 55 85.7 87 92
．． 3 selectivity, X O79,681,788
, 2 Example 4 The reaction is carried out as in Example 3, with a thermal pretreatment at 300°C and a controlled temperature of 395°C in the reactor before starting the feed of the perfluoromethyl vinyl ether stream. After about 120 minutes, a conversion of 98.6% and a selectivity of 849% are obtained. After 8 hours of 2' rolling, the catalyst shows no efficiency loss.

Example 5 The reaction is carried out as in Example 4, with the only difference that the thermal pretreatment of the reactor is carried out at 300°C. get the same result. The impurities consist of CF-CF=CF2 and negligible amounts of other fluorocarbons.

Example 6 An unfilled quartz reactor is used. The reactor was heated at 400°C for 30 minutes and at 350°C for 1 hour under N2 atmosphere.
Preheat for an hour and initially section to a controlled temperature of 330°C. Flowing a stream of perfluoromethyl vinyl ether
Supply asNlj/hour. The results obtained as a function of time and temperature are reported in the table below.

Color total time, minutes 50 60 90 120 150
180 210 T, 31 330 35
0 370 570 580 380 Conversion rate, % 2
7.6 49.4 6t5 694 82.0 95.
393.1 Selectivity 9, X 85.1 9tO89,
5B7.5 85.2 87.2 87. After running for 68 hours, the catalyst shows no efficiency loss. Impurities consist of CF, -CF=CF2 and negligible other fluorocarbons.

Example 7 A copper reactor light-filled with copper needles is used as in Example 3. The packed reactor was heated to 300℃ under nitrogen atmosphere.
Preheat for 3 hours at a temperature of 120°C.
Adjust to Nitrogen 2Nlj/hour and fluoride accumulation I Nl 7
A mixed stream of time is fed through the reactor. Then,
The reactor temperature is adjusted to 390° C. and a perfluoromenal vinyl ether stream of 0.6 Nl/hour is then flowed through the reactor to obtain the results reported in the table below.

Spring 2 Total time, minutes 535 Conversion rate, X97.5 96.0 Selectivity, % 55.0 710 This example is Example 5
It is demonstrated that active and selective rods are produced not only in the presence of reactants as demonstrated in , but also alternatively in the presence of different fluorinating agents such as elemental fluorine.

The reaction is carried out in a two-gas reactor packed with sodium aluminate powder and fed with a stream of perfluoromethyl vinyl ether at a flow rate of -mα6 Nll/hour. The conditions shown in the table below are used.

We will also report the results in red below.

Total hours, minutes 90 150 240 270 280
10 525 temperature, 'C2503003003003
30340350 Conversion rate, % 7 13.6 2B
, 5 31 53.5 75 75.8 Selectivity, %
0 0.4 49.6 51 57 59
61 Example 9 Al81 with length 250 m and internal diameter 10.911
A 316 steel tubular reactor is charged with 30 g of anhydrous MgF 2 particles ranging in diameter from 0.7 to t5. The reactor fa is heated under atmospheric pressure to a temperature of 400° C. and kept there, and a continuous flow of 6 Nl/h of perfluoromethyl vinyl ether is passed through it. After 1 hour, the exiting gas was subjected to gas chromatography: 1. I (perfluoroprobionyl fluoride (82 moles The result is an amount equal to or less than 1% o) present in 4H). The conversion rate is 97% and the selectivity is 85X. After driving for over 40 hours,
The catalyst remained generally effective.

Example 90 Before the reaction, perfluoromethyl vinyl ether was prepared by following the same manner as Example 9, except as described below, using the catalyst and operating parameters as reported in the table below. Isomerization to novel fluoroglobionyl fluoride is carried out.

1℃ 10 MgF 2 0.6 390℃958
611MgF20. (S 420°C99751
2KF 0.45 560℃ 9456 Example 1
3. 81 g F2 is used as a catalyst. The reactor of Example 9 was maintained at a temperature of 380°C, and CF5CF"2-0-C)
' = A flow of CF2 is supplied at atmospheric pressure downstream mO, 25 NJ/h. After one hour of operation, the gas exiting the reactor was analyzed as in Example 1 to determine CF3CF2CF'2CO.
The result is that it contains 90% F, a trace amount of CF30F200F=CF2, and the rest essentially consists of CF, CF=CF2. The conversion rate is 99X resulting in a selectivity of about 90%.

Claims (1)

[Claims] 1. A method for producing perfluoroacyl fluoride in which the acyl radical is a propionyl or butyryl group,
A process characterized in that a perfluoroalkyl vinyl ether in which the alkyl radical is a methyl or ethyl group is heat-treated in the presence of a catalyst selected from the group consisting of: A) a fluoride of Li, Na, K, Cs or Rb; Li, Na, K, Cs that can be easily fluorinated under the reaction conditions
or a compound of Rb; B) a fluoride of Be, Mg, Ca, Sr or Ba, or a compound of Be, Mg, Ca, which can be easily fluorinated under the reaction conditions;
Compounds of Sr or Ba; C) fluoroaluminates, fluorosilicates, fluorotitanates or fluorometalates of alkali metals or metals belonging to Group IIA of the periodic table, or easily fluorinated under reaction conditions to form the above-mentioned fluoroaluminates; D) a fluoride of a metal of the first transition series, or a corresponding metal or a compound of said metal, which is capable of producing one of the following: aluminates, fluorosilicates, fluorotitanates or fluoromethanates; E) Fluorides of lanthanides or corresponding metals or compounds of the metals that can be easily fluorinated under reaction conditions; F) Si, Al, Ti, Oxyfluorides of Ge, Sn or Pb, or Si, Al, Ti, Ge, S which can be readily fluorinated under the reaction conditions to yield one of the fluorides.
n or Pb compound. 2. Li, Na, K that can be easily fluorinated under the reaction conditions
, Cs or Rb is an oxide, hydroxide or oxyhalide. 3. Be, Mg, and C that can be easily fluorinated under the reaction conditions
The method according to claim 1, wherein the compound of a, Sr or Ba is an oxide, hydroxide or oxyhalide. 4. Fluoroaluminate, fluorosilicate, fluorotitanate or fluorometalate of alkali metals or metals belonging to Group IIA of the periodic table as K_3AlF_6
, Cs_3AlF_6, K_2SiF_6, Cs_2S
iF_6, CsCuF_3, KCuF_3, CsNiF
_3. The method of claim 1. 5. First transition series metal fluoride CuF_2,N
iF_2, ZnF_2, CoF_2, CoF_3, Cr
2. The method of claim 1, wherein the method is selected from the group consisting of F_3, MnF_2, FeF_2, FeF_3. 6. First transition series metals Cu, Ni, Zn, Cr, M
Claim 1 selected from the group consisting of n, Fe, and Co.
The method described in section. 7. Claim 1 in which the metal of the first transition series is copper
The method described in section. 8. The method according to claim 1, wherein the lanthanide fluoride is selected from the group consisting of LaF_3 and CeF_4. 9. The method according to claim 1, wherein the Si, Al, Ti, Ge, Sn or Pb compound which can be easily fluorinated to give oxyfluoride under the reaction conditions is an oxide or an oxide-hydroxide. 10. Claims 1, 2, 3, 6, 7 or 10. A metal or compound that can be easily fluorinated under the reaction conditions is fluorinated in situ by the action of a perfluoroalkyl vinyl ether or another fluorinating agent. The method described in Section 9. 11. The method according to claim 10, wherein the other fluorinating agent is fluorine or hydrofluoric acid. 12. The method according to claim 10 or 11, wherein the catalyst obtained by in situ fluorination of a metal or easily fluorinable compound is activated in situ in the presence of a perfluoroalkyl vinyl ether. 13. The method of claim 1, 4, 5 or 8, wherein the preformed catalyst is activated in situ in the presence of a perfluoroalkyl vinyl ether. 14. Claims 1, 6, and 7, in which the metal is heat-treated within a temperature range of 300° to 650°C and then fluorinated.
, 10, 11 or 12. 15. Claims 1, 2, 3, 9, 10, 11 in which a compound that can be easily fluorinated under reaction conditions is subjected to heat treatment within a temperature range of 250° to 500°C and then fluorinated.
Or the method described in item 12. 16. When using a metal of the first transition series as a catalyst,
The method according to claim 1, 6, 7, 10, 11, 12 or 14, wherein the reaction is carried out within a temperature range of 300° to 500°C. 17. The method according to claim 16, wherein when Cu, Ni, Zn or Fe is used as a catalyst, the reaction is carried out within a temperature range of 350° to 450°C. 18. Oxyfluorides of Si, Al, Ti, Ge, Sn or Pb or Si, Al, Ti, G which can be easily fluorinated under the reaction conditions to one of the oxyfluorides.
When using a compound of e, Sn or Pb as a catalyst,
16. The method according to claim 1, 9, 10, 11, 12, 13 or 15, wherein the latter reaction is carried out at a temperature in the range of 250 DEG to 400 DEG C. 19. When using fluorinated silica as a catalyst,
19. The method according to claim 18, wherein the reaction is carried out within a temperature range of 300 DEG to 400 DEG C. 20, fluorides of Be, Mg, Ca, Sr or Ba, or Be, Mg, Ca that can be easily fluorinated under the reaction conditions
, Sr or Ba as a catalyst, the latter reaction is carried out within a temperature range of 300° to 450°C.
The method described in section. 21. When using magnesium fluoride as a catalyst,
21. The method according to claim 20, wherein the reaction is carried out within a temperature range of 350 DEG to 450 DEG C. 22, fluorides of Li, Na, K, Cs or Rb, or Li, Na, K, C which can be easily fluorinated under the reaction conditions
16. The method according to claim 1, 2, 10, 11, 12, 13 or 15, wherein when a compound of s or Rb is used as a catalyst, the latter reaction is carried out within a temperature range of 300 DEG to 450 DEG C. 23. A process according to one or more of the preceding claims, which is carried out continuously by flowing a stream of perfluoroalkyl vinyl ether over the catalyst bed. 24. A process as claimed in one or more of the preceding claims, wherein the perfluoroacyl fluoride is bubbled in gaseous form into liquid bromine to purify the perfluoroacyl fluoride of unsaturated impurities.